Journal of Beijing University of Posts and Telecommunications

  • EI核心期刊

JOURNAL OF BEIJING UNIVERSITY OF POSTS AND TELECOM ›› 2013, Vol. 36 ›› Issue (1): 54-58.doi: 10.13190/jbupt.201301.54.duyl

• Papers • Previous Articles     Next Articles

A Method for Choosing the Best Frequency Range for Receiving the Compromising Emanations Form in PC Display

DU Yu-lei, LV Ying-hua, MO Fan, ZHANG Nan   

  1. School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China
  • Received:2012-05-23 Revised:2012-07-18 Online:2013-02-28 Published:2013-01-19

Abstract:

The visual display unit of a personal computer(PC) emits electromagnetic waves that contain the information from the PC display. The information signals can be received and reconstructed secretly in the far field. To choose the best frequency range for receiving the compromising emanations effectively and quickly, a method based on the common equipments is proposed. Firstly, the frequency spectrum of 10 MHz to 1 GHz are measured about 10 times respectively when the PC is displaying special image with white-black vertical strips and power off. The frequency range which may contain the display information can be obtained through frequency subtraction. And then, the special image signal is searched around the dot frequency and harmonics. If the special signal disappears when displaying the total black image, it can be judged to be the real special signal. Finally, the best receiving frequency range can be chosen by comprehensively considering the background electromagnetic noise and the peak value of the special image signal in the frequency point. Experiment shows when intercepting the computer display, the optimal image could be restored within the chosen frequency range.

Key words: electromagnetic security, compromising emanations, display pattern, eavesdropping

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